Safety and arming unit for a high velocity missile



Nov. 1, 1960 R. CALDWELL ETAL 2,958,283

SAFETY AND ARMING UNIT FOR A HIGH VELOCITY MISSILE Filed Oct. 10, 1958 I N V EN TORS,

RALPH CALDWELL FRANK C. DE LUCA FRANK M. J JS/HN H. :E US B JQMZW Q a. d iv-12 ATTORNE S United States Patent SAFETY AND ARMING UNIT FOR A HIGH VELOCITY MISSILE Ralph Caldwell and Frank C. De Luca, Philadelphia, Pa., Frank M. Jue, San Francisco, Calif and John H. Fergus, Riverton, N.J., assignors to the United States (if America as represented by the Secretary of the Filed Oct. 10, 1958, Ser. No. 766,630 1 Claim. (Cl. 102-70) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to safety and arming devices and more particularly to an improved safety and arming device for rocket propelled missiles.

In a preferred form of the invention, this improved device is mounted within the missile so as to operate only in response to the missiles temperature and deceleration rate. This has the important advantage that the device is unarmed until it nears the target. As will appear, the temperature sensitive element of the missiles control system is arranged to respond to the heat resulting from friction between the missile and the medium through which it is propelled.

The invention will be better understood from the following description When considered in connection with the accompanying drawings and its scope is indicated by the appended claim.

The single figure of the drawing illustrates an enclosure which may be a part of the missiles ogive. Mounted within this enclosure on a shaft 11 is a rotor 12 which tends to be rotated in a clockwise direction by a spring 13 but is restrained by a fusible plug 14 received within a peripheral recess in the rotor as shown in the drawing, and a creep pin 15 which extends through a wall 18 of the enclosure 10.

The plug 14 consists of an alloy which melts at a low temperature. By a judicious choice of alloys, heat paths, heat capacities, spring tensions and rotor mass, the time the plug 14 melts is adjusted to such a value as to meet the arming requirements of the missile.

In the extended condition of the spring 17, the pin 15 engages a slot or recess 19 of the rotor 12, thus forming a deceleration sensitive coupling between the rotor 12 and the enclosure 10. In order for the pin to be withdrawn from this slot, the missile must be decelerating at a rate dependent on the resistance of the spring 17. When this happens, the rotor 12 is turned clockwise by the spring 13 upon being uncoupled from said enclosure 10 by both the fusible plug 14 and the creep pin 15, bringing a detonator 20 into operative relation with an explosive train 21. This explosive train is located in a firing chamber which is at the rear end of the enclosure 10 and has an opening 22.

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As will be obvious to those skilled in the art, the detonator 20 may be arranged to complete a firing circuit at the time it is brought into operative relation with the explosive or to ignite the explosive in any of the various other ways common to the art. Among the advantages of the present invention may be mentioned appreciation of the desirability for elimination of both acceleration and centrifugal force as factors along with timing mechanisms in either the safe locking or in the arming of this unit whereby an important reduction in number of parts and enhanced foolproofness has been possible. This has been by retention of both deceleration and temperature responsive mechanisms in the present safety and arming unit.

We claim:

In a safety and arming unit for a high velocity missile having an enclosure adjacent a firing chamber, a shaft, a rotor thereon and movable from an unarmed position to an armed position into alinement with an opening in said firing chamber, a fusible coupling operatively disposed between'said rotor and said enclosure, and a deceleration coupling between said rotor and said enclosure, the combination therewith of the improvement for simplification in said unit, for reduction in the number of parts in said unit, and for elimination of centrifugal force in the arming of said unit, said improvement comprising said shaft being stationary with respect to said enclosure, a spring around said shaft fixed at one end to said enclosure and at an opposite end to said rotor for angularly displacing said rotor when uncoupled from said enclosure for arming said unit, said rotor being provided with angularly spaced recesses into one of which a creep pin is received to constitute said deceleration coupling and into another of which a fusible plug is received, to constitute said fusible coupling, each of said creep pin and plug holding said rotor against rotation while coupled with respect to said enclosures, said plug being in thermally conductive contact with a wall of said enclosure, and a spring cooperating with said creep pin and enclosure for retaining said creep pin in its rotor recess while said enclosure is accelerating but said spring being compressible on deceleration of said enclosure and withdrawal of said creep pin from its rotor recess, and a detonator received within a peripheral recess of said rotor substantially opposite to said fusible plug and its recess for directing a flame into said firing chamber after said rotor has been angular-1y displaced by said first mentioned spring upon said rotor being uncoupled from said enclosure by both of the fusible plug and creep pin, whereby the number of moving parts has been greatly reduced with enhanced foolproofness upon elimination of centrifugal force as a necessary element to the unit being armed.

References Cited in the file of this patent UNITED STATES PATENTS 

